Posted
by
timothy
on Friday September 03, 2010 @04:28AM
from the string-washing-powder-what's-the-difference dept.

dexmachina writes "A team of theoreticians, led by a group from Imperial College London, has released calculations that show string theory makes specific, testable predictions about the behaviour of quantum entangled particles. Professor Mike Duff, lead author of the study from the Department of Theoretical Physics at Imperial College London, commented, 'This will not be proof that string theory is the right "theory of everything" that is being sought by cosmologists and particle physicists. However, it will be very important to theoreticians because it will demonstrate whether or not string theory works, even if its application is in an unexpected and unrelated area of physics.' In other words, string theory may finally have shed its critics' most common complaint: unfalsifiability. However, given the second most common complaint, I can't help but wonder: which string theory?"Update: 09/03 23:34 GMT by S: Columbia University's Peter Woit, author of the Not Even Wrong blog, says these claims are overblown, and adds that a number of string theorists said as much to Wired.

Indeed, it's worse. While I don't know much about string theory, I do work in the field of entanglement. And there's no way you could experimentally test this classification, for the simple reason that it's a classification. It may be a more or less useful classification, but you cannot experimentally test whether a classification is right (apart from that an reasonable entanglement classification has to be SLOCC invariant, which this classification is, but of course the others are as well). Trying to experimentally test if a classification is right is like doing an experiment on whether classifying a fruit on its color or on its size is more correct. What you can do is to evaluate the usefulness of a classification (i.e. does it tell you something interesting about the state, like what you can do with it; in the fruit example, you might find that classifying fruits on nutrition value may generally be more useful than classifying on water content).

At this University at least, PR for specific projects is driven by the PIs themselves. Anything in a University press release has been provided by the PI and drafts of the press release have been fact checked by the PI. In other words, if there's a problem or a exaggerated claim, blame the scientist.

But if they accept that it disproves that theory, then they may get a boost in credibility. From being incompetent liars to being merely wrong. Which for string theorists would be a substantial step up in terms of actual credibility.

I scanned through the article and from what I see, they have made an equivalence between the maths used in string theory and the maths used in entanglement. This is interesting in itself, because this allowed them to port a result from string theory to entanglement theory, a result which was not known before and could be falsified.

However, this is like saying that the mathematical theory used to count apples harvested from an orchard (addition of natural numbers) is the same as the mathematical theory behind the algorithm the slashcode uses to count the number of comments below threshold (addition of natural numbers). It allows one to port result from ancient mathematics to modern applications without having to rederive everything from first principles; it does not mean that sub-threshold comments are, deep down, really made of apples.

However, this is like saying that the mathematical theory used to count apples harvested from an orchard (addition of natural numbers) is the same as the mathematical theory behind the algorithm the slashcode uses to count the number of comments below threshold (addition of natural numbers). It allows one to port result from ancient mathematics to modern applications without having to rederive everything from first principles; it does not mean that sub-threshold comments are, deep down, really made of apple

As a physicist, I do get a bit annoyed at the constant attacks on string theory in public media.

Let me just state a few points please:

* We have Quantum Mechanics for the realm of the very small
* We have General Relativity for the realm of the very heavy
* Both of these theories fit observational data and work very well
* The two theories contradict each other in the case of very heavy and very small object (e.g. tiny black holes)

So, we need a new theory that gives the same predictions at QM and GR in the realms that we can measure them. This is where string theory etc comes in. But we do not yet have experimental data for very heavy and very small objects. If you want to complain about string theory not being testable, then accept that your same complaint is going to apply to EVERY grand-unified-theory that we know of.

Conclusion=========

If you complain at string theory, then PLEASE state what you are proposing. What is the use in complaining when you have no alternative? The main scientific proponents against String Theory also just happen to have their own pet theories (e.g Quantum Loop Gravity) which are in an even worse situation.

If you complain about string theory taking so long, then what do you expect? It has taken 16 years just to do a single experiment (The LHC).

The only way we can make String Theory etc testable is by further research. If you dislike, please propose a better solution rather than just complaining.

No, it's nylons... and they only go down from the thigh (otherwise we're talking about pantyhose, which are a creation of the devil.) From the thigh up, it's garters. If you find turtles, retreat immediately. It's likely to get worse, and you don't want to know about that... guys that want to know about that become gynecologists. And no one with any sense at all wants to encounter dark matter. Also, garters first, panties (optional, of course), second.

Experimenting in this realm is highly recommended. Repeat a lot - you want to be sure.

So wait, we have two theories that describe different realms and no data for the intersection of the two realms, but people are trying to come up with a theory for the intersection?

We know that very very small objects exists (subatomic particles). We also know that very very massive objects exists (stars).

Usually the two are linear. The smaller an objects, the less mass it has.

Unfortunately there IS a crossover point. There are objects with a density of approximately 370,000,000,000,000,000 kg/m^3. These can be modeled with regular physics for 'large' objects, and they affect things far outside the realm of Quantum Theory (i.e. you can orbit a human around such an object). Get too much above this point though, and you end up with an object that seems to be smaller than the smallest subatomic particles (Quantum Theory) yet affects things that are far outside the realm of Quantum Theory - these items are commonly known as black holes.

How do they work? Well... they're insanely massive. And they're really tiny. As to what goes on inside them... we've no clue. We can't use Quantum Theory because it's too massive, and we can't use regular physics, because it's too small.

How do they work? Well... they're insanely massive. And they're really tiny. As to what goes on inside them... we've no clue. We can't use Quantum Theory because it's too massive, and we can't use regular physics, because it's too small.

How do you know they are tiny? Sure, GRT predicts a singularity. But has anyone ever actually measured the size of a black hole's mass distribution beyond the event horizon?

So wait, we have two theories that describe different realms and no data for the intersection of the two realms, but people are trying to come up with a theory for the intersection?

Um, the cross-over objects exist. Grandparent poster is wrong, you don't need small black holes; any singularity has the problem of needing quantum mechanics and general relativity to describe it. This is true of the inner workings of any black hole, for example. (No, we can't get data from one, as far as we know.) Or, just fer instance, the Big Bang. There is a surprising amount of interest in modeling that one.

So wait, we have two theories that describe different realms and no data for the intersection of the two realms, but people are trying to come up with a theory for the intersection?

We have two theories that describe different realms (although not the realms mentioned in the summary) and we have a known isomorphism between the mathatical description of one of them in stringy terms and the behaviour of the other. This paper extends that isomorphism into a currently intractable area.

So it's more like saying you know that people who can drive Fords can also drive Toyotas, but Toyota has just come out with a new model that none of the Toyota drivers can handle, so why not give it to a For

>Unless you're suggesting that it isn't possible, but that's really just another theory that you're going to have to justify in the same way.

That's quite easy. Black holes are formed when gravity overwhelms all other forces, which I take to mean nuclear strong/weak forces. (If you look at a neutron star, it's density is the same as a nuclear density.)

In everyday life, it takes about 7000 cubic kilometers of volume before you have enough space to pack in enough mass to do this (calculated from a 12km sc

Since string theory cannot be distinguished from , e.g., QM (i.e., string theory is untestable), does that not also imply that QM cannot be distinguished from string theory (i.e., QM is untestable)? So why is QM given precedence?

I think the public media attacks string theory on the grounds of its impossibility to test because they don't know any better. Those of us in physics and math have very real and strong arguments against string theory that have little to do with testing.

Is that it isn't. What I mean by that is it doesn't seem to make any testable predictions. At this point, it is just a bunch of math wanking. Now there's nothing wrong with purse math. A lot of useful theories start out that way and I like the Bacon quote "If in other sciences we should arrive at certainty without doubt and truth without error, it behooves us to place the foundations of knowledge in mathematics."

However when all you've got is a bunch of neat math with no real testable predictions, it is not a theory and it is not the sort of thing to be crowing about to the general public. XKCD, as usual, did a humorous job summing it up: http://xkcd.com/171/ [xkcd.com].

If you are going to complain that people complain about the lack of testability then you need to do two things:

1) Read The Logic of Scientific Discovery again and brush up on what a theory is and isn't.

2) Don't go making press releases. I'm not saying you personally have done this but physicists are awful happy to talk to the press about something they can't prove.

Part of it is simply wanting accuracy in the use of the words because let's face it: In science accuracy matters. Being pedantic about terms is important in science. Another part of it is this is the kind of thing that confuses normal people. With evolution, scientists have gone to a lot of trouble to explain that a theory is NOT a guess, NOT a wild idea, etc. They show other theories and how they work, how many things we accept as true are theories.

Well something like this undermines that to an extent, because here is something being called a theory that is not only untested, but that they can't even figure out how to test. It is the kind of thing that can make people say "But wait, if this is a theory then theory doesn't mean what you said."

...then let's not throw around phrases like "theories accepted as truth."

A much better way to construct such a remark is "theories we presently have (very|extremely|) high confidence in."

Because I gotta tell ya, "truth" is one of those nasty words, like "belief", that usually - outside of logic and math, where it means something else - means someone is glossing over something, and it's probably not insignificant.

Just saying. You want a way to write about worldviews - including scientific ones - that

I'm speaking of regular individuals. Yes I understand that when you get down to it, nothing outside math can be prove true as in no room for anything to dispute it ever (and of course just because something is true in math doesn't mean it applies in the world, could all just be in our heads). However normal people accept things as true, and they accept much of science as true. So truth is a useful thing to talk about.

I guess I'm currently in the 'so what' camp. If a String Theory covers all of QM, Relativity, and Gravity, and it makes useful predictions that can be tested and leads to further knowledge and useful engineering - I guess I don't really care if the underlying assumptions are right or not.

By all means, keep working on something better, but if the above is true, it's a good theory to work with. We got quite a bit of useful work done with Newtonian physics, and QM/QED have gotten us much further, even if the

So, we need a new theory that gives the same predictions at QM and GR in the realms that we can measure them. This is where string theory etc comes in.

Not really. Last I checked, String Theory hasn't made any useful predictions about systems like this. No one has managed to fold gravity into a Theory of Everything yet, unless I missed an important update. (Feel free to correct me if I have.)

TL;DR - People complain at string without proposing anything better.

A theory that offers no new powers of explanation and prediction is itself no better than the pre-existing paradigms. Until String Theory can show itself to have some value (leaving aside the issue of whether it's the best such model), there's no reason to cling to

Actually, it seems to me like we don't call those grand-unified things a proper scientific theory either. As long as there are no testable predictions, and it fails Occam's Razor, it's not a theory, plain and simple. It's a hypothesis.

Yes, there is a name for a theory which hasn't yet been tested: hypothesis.

And really, as someone who's gotten tired of hearing Young Earth Creationists go "well, evolution is just a theory" and having to explain to them "yeah, but theory in science doesn't mean what you think. It means it already made testable predictions and is the best we have"... it's getting annoying to see that a whole bunch of physicists are actually using it exactly as the YECs and conspiracy theorists think: as just an untested and untestable supposition, which may or may not actually hold any water at all.

Yes, I realize that calling it a "theory" is more science-y sounding and good for your funding. But it devalues the whole idea of science for everyone. If we accept that some untested and untestable calculation is just as worthy of being called a "theory" with a straight face as GR or electromagnetism just because it's the pet supposition of some physicist, then basically why wouldn't Behe's pencils-up-the-nose ID idiocies be a "theory" too? I mean Behe _is_ a professor of biochemistry.

Call it the String Hypothesis, and you'd see a lot less complaints, basically.

Thanks you for supporting my point of view - you should create an account, then I could become a fan:)
However, I disagree with mathematics including physics. I consider mathematics as being a tool or even a language used by physiscs.
Disclaimer: I'm neighter a mathematician nor a physicist (I'm a logician.)

Haxamanish is correct. In mathematics (which basically includes physics), any body of axioms and resulting theorems is a "theory", even if it doesn't have (known) real-world application.

It's a subtle point, but math itself is not science. One doesn't derive testable hypotheses of the physical world from pure math. It's only in applying math to physical phenomena, that it has scientific value. In particular, just because something is called a "theory" in the mathematical sense, doesn't mean that it is a theory in the scientific sense. "Ring theory" is a good example of this.

Having said all that, I do agree that Hexamanish is correct. It's just that we need to be a bit cautious when drawi

As long as there are no testable predictions, and it fails Occam's Razor, it's not a theory, plain and simple.

I hate Contact, I hate Contact, I hate Contact.

Because Carl Sagan had a misunderstanding about what Occam's Razor is, but nevertheless explained it wrongly in Contact, now millions of people have been introduced to the concept as explained by his novel or the movie. "The simplest explanation is usually the correct one" is not Occam's Razor. Occam's Razor says nothing about correctness at all, and it's most certainly not a requirement to create a scientific theory. All it actually says is that if two theo

Where did I say I was using the one from Contact or anything. Yes, I'm using largely the version you explain there: as long as two hypotheses explain the exact same sets of measured data, go with the less complex one, leave the more complex one for when you actually have some data that the other one can't explain.

In exactly that sense, as long as the String Hypothesis doesn't have at least one testable prediction [b]of its own[/b], that can't be explained by the simpler GR and QM, it freaking fails Occam's Razor.

It doesn't mean it's _false_ and nowhere did I say it's _false_. I said until such time as it makes testable predictions of its own, it's just a _hypothesis_. Different thing from "false".

So basically, what, you made all that fuss to answer to your own strawman?

You can criticize a theory without proposing anything better if you don't have a theory yourself - because you can point to flaws in the other theory. Observations that seem to go against the theory, the impossibility of falsifying the theory, etc.

For example, I can point at "intelligent design" and say it's a bad theory because it is not falsifiable and I don't have to offer an alternative theory of ab

If you want to complain about string theory not being testable, then accept that your same complaint is going to apply to EVERY grand-unified-theory that we know of.

And why do you think this would be a problem? My complaint about the Christian god not being testable does also apply to other deities, but the Christians are the ones pissing in my back yard, so those are the ones I complain about. Similar with the string faith.

If you complain at string theory, then PLEASE state what you are proposing.

If you complain at string theory, then PLEASE state what you are proposing.

I never get this line of argument. Surely if you've got evidence that demonstrates a particular theory is clearly wrong, it's better to flag that up even if you've not got any specific alternative. If nothing else, it should encourage others to stop wasting their time pursuing something that's clearly wrong.

I'm not saying that string theory is wrong (I'm not a theoretical physicist, and I've got no particular views on this theory), b

Not so. There are a variety of more-or-less heuristic alternatives to string theory, they just don't have supporters that are quite so grandiose and arrogant as string theorists.

The problem with string theory is that it is uniquely hard to build models of low-energy systems using any of its variants, which is funny because it has been applied in pure form to various solid-state systems. But due to extremely high string tension (or equivalent parameter) that is necessary in the "theory of everything" strin

String theory poses to the general public as what modern physics is. Take a look at the books available at a bookstore, science articles at the gernal press, etc. All you'll see is bold predictions about how our universe fist within a multiverse, how string theory explains the inner workings of a black hole, and so on. There is nothing wrong with you working on string theory, your PR department just needs to stop presenting it as a certainty.

You know what, just for that, from now on I'm going to call it "String Hypotheses" until such a time as somebody actually successfully falsifies something. And then comes up with a test that seems to work. It doesn't matter whether anybody has anything better to go on, the fact is that until they start to falsify things when they fail, it isn't science, it's a weird religious fetish for atheists.

If you complain at string theory, then PLEASE state what you are proposing. What is the use in complaining when you have no alternative?

As I read your post, and especially this part, I was struck by how wrong I consider this sentiment.

Science is about the search for answers, the search for truth, and we have spent the better part of our history refining what we think to be important in that search. "I don't know what the answer is, but that is wrong" is and should always be a perfectly valid answer.

While we are trying to use maths to solve pretty much everything, maybe the thing that is flawed is our numbering system?!?

Remember the roman numbers? It was supposed to be the most logical thing in the world back then. Then we came up with base 10 / positional numbering system. All of a sudden, everything was simpler, everything was easier to calculate, and it opened up our eyes on a lot of things.

But then, maybe we reached the end of what our numbering system / way of thinking about maths, can do.

Your poster tells that you aren't good on math or physics. Just as an example, QM doesn't rely on 'our nunbering system', almost all calculations are made on a Hilbert space, based on the Dirac delta function. There are no numbers as you know them there. Ok, sometimes a real nunber pops from a calculation, but that is normaly just after all the heavy stuff.

Actually it's pretty solid, the only thing in the last 200 years or so that it's really screwed it up was when somebody disproved the fifth postulate [wikipedia.org]. Which is to say that it wasn't the numbers that were the problem it was the presumptions we were making about reality which were. And right after the work to disprove it was completed all kinds of really amazing discoveries were made. There's still a lot of things like that out there to do, the biggest one is that there's a tendency to assume that because it

The thing is, decimal didn't make everything simpler and easier to calculate and open up our eyes. It feels that way, because you've spent you're whole life using it and everything else feels weird and foreign. Base 10 feels natural because we have 10 fingers and 10 toes (among other reasons).

But you can see the evidence of our history of using base 12 from our words for numbers (this is the reason eleven and twelve aren't firsteen and seconteen). Base 12 is also very natural because it has so many factors

The second most complaint I have with String Theory is how ordinary people can possibly understand the mathematics. I can just about grasp Einstein, Tensors and so forth. Multidimensional manifold's, M-theory and the like leave me feeling intellectually inadequate. Is it all just some obscurantist joke, or is reality really that complicated?

Well, I'm just a layman too, but I rely on the word of some math specialists, that confirmed that it indeed is that hard. Anyway, there is no requirement on the scientific method that your theory must be understandable by lay people, or even by specialists of the area, it must be as complex as the data requires.

My head hurts. You took the correct phrase in the summary "its (plural) crtics' (plural possessive)" and turned it into the mind bending "it's (contraction - it is) critics (plural)". Twice. With bold face.

Just for the record: Gödel did not proof math to be not consistent. He showed two things:

1. That in every axiomatic system strong enough to capture aithmetic there necessarily are true sentences that can be expressed with the means of the system but cannot be deduced from the axioms (he presented a method to construct such sentences).

2. You cannot deduce a system's consistency from the axioms of such a system. (Which is something completely different from prooving that math is not consistent).

Well, propositional logic can be proven to be consistent (there are no contradictions) AND complete (all true propositions can be proven out of the axioms), so can first order predicate logic (in the PhD dissertation of Gödel, 1929 [stanford.edu]).

To construct arithmetic out of logic, we however need second order predicate logic. Gödel (1930, published 1931 [wikipedia.org]) showed that axiomatic systems in second order logic are either incomplete (true non-provable sentences can be constructed) OR they are inconsistent (containing contradictions).

"You can NOT say that math (arithmetic) is consistent, that's WRONG. You *can* say it's inconsistent"

No, you can NOT say that it is inconsistent, and you can NOT say that it is consistent. The fact that you prove you can't say some A doesn't automaticaly makes NOT A true.

"There are no known ways to construct real numbers that are not simple extensions of rational numbers."

Having a bit of trouble with math, isn't you? What are you proposing to construct the real numbers of? Rational numbers? If so, that is just a tautology. You don't need to construct the real numbers, as you don't need to construct the natural numbers. You don't proff that math exists, that doesn't make sense (well, except if you define "exist" in some mathematical way, but then, you'll be just applying your definition).

Hmm, where is the -1 "Woefully misinformed" moderation when you need it.

It's not just that the consistency of Peano arithmetic cannot be proved inside Peano arithmetic, it can't be proved, at all (in any meaningfull way : the only way to "prove" it is to accept it's correctness as axiom).

Well this is just wrong. You can indeed prove the consistency of Peano arithmetic if you're willing to go outside it. Specifically you can use Gentzen's consistency proof [wikipedia.org], which doesn't "accept the correctness of Peano as an axiom" (but has other limitations). To add further weight to this, you may note that the Incompleteness theorems state that the system will either be incomplete (have unprovable truths) or inconsistent; Peano arith

Well hell, I still haven't given up believing in the aether. or that ghosts can pass through solid objects, except for the floor. A man's not a man without something to believe in, I say. Nixon for President in '012. And I have a proof a bit too large to scribble in the margin here about P and NP.

[...] or assuming the correctness of math before Godel (who proved math is not consistent, whoops)

You got to improve your trolling - you have to be irrational and coarse enough to be enraging, yet not so loony that you self-identify as a troll. I rate you a 6 out of 10 for aggravating, which is OK I guess. What puts you over the top is stating that Godel proved that math is inconsistent. At that point the trolling just becomes too obvious.

Indeed, it's one thing for a test to come inconclusive, but when it comes back that the hypothesis was false, there's limited scientific responses to be made. You can conclude that there was a different mechanism involved or that it wasn't happening in the first place. The problem is that when you start asserting that the results would've been correct in some other reality which you can't directly observe, you end up with something that's about as scientific as any of the world's religions. Including that o

"What you call love was invented by guys like me to sell nylons. You're born alone and you die alone and this world just drops a bunch of rules on top of you to make you forget those facts."
-Don Draper, Mad Men

I don't believe in God, but if he (i'll use the 'he' pronoun for convenience) exists then he's the one making up the rules not us, so 'testing' for God is a bit dumb. We can prove that the universe could have happened without God but we can't prove he doesn't exist.

And if he does exist I bet string theory is giving him the best laugh he's had in centuries:)

Unfold your wisdom on poor me and explain what you are talking about. What is insulting the English language is "Apologizing for referring to the Christians' god as a he". It is not "he" who insults the English language. What am I missing?

You a) failed linguistics, b) are an idiot and c) just built a huge strawman so you could burn it down. You must be proud of doing it in the kind of forum where, to boot, you will likely find like-minded idiots to applaud the strawman.

You do realize that the german word for woman is not derived from the german word for man, thus making your point even more ridiculous, right? Similarly, german "humankind" is Menschlichkeit, not "Mannlichkeit".

First off, I didn't make a typo. The word "man" is not the same as the word "Mann" is in German, which apparently you didn't know. Making it more than a little bit ironic that you're calling me an idiot when you didn't even know that.

Secondly, it's a legitimate follow up to assert that feminists get caught up in that out of bigotry and ignorance given that they aren't aware that the ultimate roots of it goes back ultimately to German via old English. Where it ultimately was derived from "wifman" as in ba

Yeah I re-read that after i'd hit the final submit and wished i'd worded it differently. The proof would require some assumptions that "the big bang happened because the big bang happened" and that "the rules of the universe are what they are because they are what they are". From that point on we can (in theory, eventually) prove that everything that happened since happened by following those rules.

The rules may also describe why the big bang happened too, but the reason for the rules being what they are is

ignorance and vanityfirst there were spirits everywhere, then as we learned to understand the world, these became pantheons of gods, then as we learned more, reduced to the one god. God is then just our ignorance of the world and the vanity of those who cannot answer 'i do not know'.

God is then just our ignorance of the world and the vanity of those who cannot answer 'i do not know'.

You say that like it's a bad thing. Even if science explained every last little detail of the universe, there is no way that the majority of people are going to understand it without devoting their entire lives to doing so. As far as they are concerned scientists telling people that there is no God are just as bad as the crazy guys standing on the street corners telling people that Coke and Pepsi are the same thing.

A belief in God gives some people tremendous comfort in a world that otherwise doesn't give a